Oxidizing salts such as but not limited to ammonium nitrate, ammonium perchlorate, and urea nitrate have many industrial uses. Unfortunately, these strong oxidizing compounds may also be incorporated into homemade explosive devices. In particular, a high explosive known as ANFO (ammonium nitrate fuel oil) is easily prepared by combining ammonium nitrate with number two fuel oil or diesel fuel. A typical formulation for ANFO utilizes about two quarts of fuel oil and about fifty pounds of ammonium nitrate. Although commonly used in the mining industry, the simple process for preparing ANFO also makes it a ready formulation for terrorists. Thus, the ability to readily detect the presence of oxidizing salts will be beneficial to the detection and prevention of attacks using explosives based on oxidizing salts.